What Is ASCVD?

Cardiovascular disease is a catch-all term for health conditions that affect the heart (“cardio”) and blood vessels (“vascular”). The term “atherosclerotic” describes conditions that are caused by the build-up of plaque inside the arteries (blood vessels that carry blood from the heart to tissues and organs around the body). This build-up can affect arteries anywhere in the body.
Plaque is made up of cholesterol and other fats and substances. It is thick and sticks to the internal walls of arteries. Over time, it can build up and cause arteries to become narrower. They may also harden and lose their elasticity. As the spaces inside arteries become narrower it becomes more difficult for blood to flow through them. This puts strain on the heart and causes cardiovascular disease. The term “ASCVD” is used if the build-up of plaque results in conditions like:

• peripheral artery disease (damage to the peripheral arteries in the legs and arms),
• stroke and heart attack (these can be caused if plaques burst, resulting in the production of blood clots that can suddenly block the flow of blood),
• angina, or
• aortic aneurysm.

Preventing Atherosclerosis

In its early stages, people do not usually experience any signs or symptoms of atherosclerosis, so it is difficult to know whether plaque is building up in your arteries and to what extent. The good news is that as well as being treatable, atherosclerosis can be prevented by making healthy lifestyle choices such as not smoking and having a healthy diet. Exercising regularly is also important, with some describing physical activity as a “miracle drug” on the basis of its health benefits and association with longer lifespan.

Why Is Being Physically Active Important?

Regular physical activity has long been known to have a protective effect on the heart and arteries. It is also linked to “cardiorespiratory fitness”, which is a measure of how well the heart and lungs supply oxygen to a person’s muscles while they exercise. When matched with fitter individuals with similar profiles of other risk factors, people with low cardiorespiratory fitness have been shown to have a three times greater risk of dying prematurely from ASCVD. Studies have also reported that the risk of developing heart failure is reduced, and the chance of surviving it increased, when people become more physically active.

How Much Physical Activity Is Enough?

Guidelines published by the World Health Organization recommended that people should be physically active for at least 150–300 minutes per week if the activity level is “moderate” or 75–150 minutes per week if the level is “vigorous” (or a combination of the two). Activity is considered moderate if your heart beat gets faster and you start to breathe faster and feel warmer while you are doing it. You can easily hold a conversation if you are exercising at this level, and examples include brisk walking, swimming and cycling, and dancing. Some studies have even reported that people who walk more briskly have an increased chance of having better long-term health.

If you increased your level of activity to vigorous you would start to breathe fast and hard, and you would only be able to say a few words at a time. Examples of vigorous activity include running, swimming lengths quickly, cycling uphill or as fast as you can, and aerobics. However, it is not simply the case that a huge amount of vigorous exercise (such as running a marathon) is always better. High-volume and high-intensity training regimens are not needed for people to gain the benefits of cardiac conditioning (activities that increase oxygen consumption and heart rate), with one study reporting that the survival benefits gained through vigorous exercise seem to level off beyond an average of 35 minutes per day.

It is also worth noting that the potential benefits of people increasing their levels of “light” physical activity (such as light household chores or slow walking) can be significant. Studies have reported that higher levels of light physical activity are similarly associated with reduced risk of cardiovascular disease, with one reporting that with each 30-minutes-per-day increase in light physical activity, the risk of death from cardiovascular disease decreased by 20%.

Although the cardioprotective effects of light physical activity are less than those of moderate-intensity activity, it is relatively easy for people to increase their levels of low-intensity activity and it can be done in small blocks of time that add up over the course of the day. Even though the authors note that the benefits of light physical activity have been understudied to date, several studies have reported health benefits when people add repeated periods of physical activity for as little as 2 minutes at a time to their normal daily routines.

What Type of Exercise Routine Is Most Effective?

There is some evidence that high-intensity interval training (HIIT), where short periods of high-intensity activity are alternated with periods of lower-intensity activity or resting, can be more effective in improving cardiorespiratory function than continuously exercising at a moderate rate. This has been shown to be particularly true when the total amount of “work” undertaken in the training sessions that are compared is the same.

HIIT has also been reported to be safe when used as part of cardiac rehabilitation. These are supervised programs of exercise and information provision that support people diagnosed with or recovering from serious conditions like heart failure and heart attack, or who have undergone heart surgery. However, it’s important to gain advice from a medical professional before increasing your physical activity if you are recovering from a heart condition.

The authors of the review suggest that structured exercise sessions should consist of the following:

1. a 10-minute warm-up where the person exercises gently,
2. an aerobic conditioning phase during which the activity is more vigorous, and
3. then a 5- to 10-minute cool-down phase.

To improve aerobic capacity or cardiorespiratory function, people should aim to train at an intensity that corresponds with 40–70% of the highest heart rate that they achieve during peak exercise testing.

For people who have not undergone exercise testing recently, the authors suggest that they use their standing or resting heart rate plus 15–25 beats per minute as a guide of ideal exercise intensity, using perceived exertion as an additional indicator (for example, exercise perceived to be “somewhat hard” or “hard” after an initial 4–6 weeks of training at a level rated as “fairly light” or “somewhat hard”). Age-predicted maximum heart rates can also be useful to work out how intensively you are working. Broadly speaking, your age-predicted maximum heart rate (in beats per minute) is 220 minus your age, with moderate-intensity activity representing a heart rate that is 50–70% of this value, and vigorous-intensity activity being 70–85%.

Another useful measure of activity is the number of steps taken per day. The authors note that although greater daily step counts are associated with more significant health benefits, studies reported to date suggest that the minimum number of steps needed to reduce the risk of adverse health outcomes seems to be between 2,500 and 4,000 steps per day, although in those younger than 60 years the ideal number of steps may be slightly higher.

The authors conclude that “exercise is medicine”, and that an exercise “prescription” can significantly improve the health of people who are inactive. These benefits can be realized through relatively small increases in physical activity at a time, which is something that most of us can achieve.